Method and apparatus for conditioning refuse

ABSTRACT

A method and apparatus for treating refuse by non-combustibly shrinking polyfoam plastics in the refuse. The trash is heated at a temperature between 250° and 500° for a minimum period of time. A rotatable chamber heats the refuse and transports the refuse for the minimum period of time. An operator controls the rate of rotation of the chamber and thus the time of heating in accordance with the moisture content of the refuse. A steam/air mixture used as a heat medium serves to kill bacteria in the refuse in addition to shrinking. and drying the refuse.

CROSS REFERENCE TO RELATED APPLICATIONS (35 U.S.C. §120)

This application is a continuation of application Ser. No. 07/888,562,filed May 22, 1992 by Frank T. Romweber and Dennis F. Sowa, now U.S.Pat. No. 5,412,881, which is a divisional of application Ser. No.07/698,355 filed May 6, 1991, now U.S. Pat. No. 5,116,363, which is acontinuation-in-part of application Ser. No. 07/475,995 filed Feb. 6,1990, now abandoned, which is a continuation-in-part of application Ser.No. 07/410,093 filed Sep. 20, 1989, now abandoned. Each of the aboveapplications is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to the disposal/treatment of refuse in the form ofsolid waste material, and more particularly to a method and apparatusfor conditioning refuse by the noncombustible shrinking of polyfoamplastic material as one stage in the refuse disposal process.

Over the past 10 years, the quantity and character of household refuseand fast food refuse has changed measurably. The amount of trashgenerated has increased per person per day and the population hasincreased by some 30 million people. It is believed that the dailyamount of trash for disposal in 1980 has increased by about fortypercent (40%), while available disposal space has been decreasing.

The commingled household waste of today contains a very large percentagemore of plastics and aluminum than household waste did 10 years ago. Themethods for disposal include landfills, incineration and householdseparation of certain recyclable items with separate pickup for eachitem being necessary. All three methods are becoming increasinglyexpensive. In addition, it is very difficult to recycle recyclables ininner city trash by existing methods.

It is particularly desirable to have a method for disposing of andrecycling certain municipal solid wastes both safely and economicallyand in a manner that does not harm the environment. Wastes from varioussources including households, fast food restaurants and other commercialestablishments including airports, sports arenas and other businessescontain cups and dishes made from polyfoam plastic material. The burningof such polyfoam plastics poses direct problems to the environment fromthe resulting exhaust gases. In addition, the dumping of such materialsat land storage locations also effects the environment in that suchplastics are not generally biodegradable and occupy an inordinatelygreater volume.

It is therefore an object of the present invention to optimize therecycling of certain municipal solid wastes safely and economicallywithout harming the environment.

It is a further object of the present invention to provide a method andapparatus for the disposal of polyfoam plastic type material includingfoam cups, dishes and containers. It is a further object of the presentinvention to provide a method and apparatus for preprocessing ofpolyfoam plastic materials such as foam cups and dishes in order toprepare the refuse for a subsequent sorting processes of recyclable andobjectionable inorganics.

It is an additional object of the present invention to provide aconditioning stage in a waste disposal system which may be includedwithin presently existing solid waste disposable facilities.

It is a further object of the present invention to optimize the recoveryof aluminum, steel, plastic, glass, textiles and waste paper by treatingthe refuse before sorting.

It is an additional object of the present invention to have a method forshrinking polyfoam plastic materials, thus requiring far less volume foran eventual disposal site or for separation and recycling.

It is a further object of the present invention to shrink noncombustiblylarge volumes of polyfoam material quickly and safely in order toprepare the material for recycling.

SUMMARY OF THE INVENTION

These and other objects of the invention are achieved in a method andapparatus wherein refuse including polyfoam plastics is heated at atemperature of between 250° and 500° for a minimum period of time,causing non-combustible shrinking of the polyfoam plastics.

One of the disclosed embodiments causes the drying and sanitizing of therefuse stream in general, and the trash is separated with objects 6inches and smaller being drawn off separately for easier recycling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of a system using a preferred embodiment of therefuse conditioner of the present invention.

FIG. 2 is a partial side view of the refuse conditioner of FIG. 1.

FIG. 3 is a view taken along a section 3--3 of the conditioner of FIG.2.

FIG. 4 is a front view of a nozzle ring of the conditioner of FIG. 2.

FIG. 5 is a side view of the nozzle ring of FIG. 4.

FIG. 6 is a side view of an injection tube of the conditioner of FIG. 2.

FIG. 7 is an end view taken along a section 7--7 of the conditioner ofFIG. 2.

FIG. 8 is an enlarged side view of a portion of the injection tube ofFIG. 6.

FIG. 9 is an enlarged end view of the injection tube of FIG. 6.

FIG. 10 is an end view of a drop out box of the conditioner of FIG. 2.

FIG. 11 is a side view of the conditioner of FIG. 1.

FIG. 12 is a view taken along section 12--12 of the conditioner of FIG.11.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, municipal, commercial, household and/or fast foodsolid waste 11 is collected by a truck 13, or by other means. The wasteis culled of large objects such as old appliances, hot water heaters,tree stumps, yard wastes, etc., and then dumped into a refuse inletpassage 15.

It is not necessary to presort raw refuse such that only polyfoamplastic materials enter inlet passage 15 The raw refuse in its "as is",unsorted state is fed into inlet passage 15. The input refuse is notshredded or otherwise processed prior to input. The present system istolerant of handling all household wastes in addition to polyfoamplastics without harm to the environment. "Polyfoam plastic" as usedherein shall mean plastic having gaseous bubbles randomly trapped withinthe plastic.

A rotating conditioning chamber 23 receives the solid waste from inletpassage 15 and heats the waste for rapid drying and shrinking ofpolyfoam plastic materials. Such items as foam cups and foam traysshrink to 1/5 of their initial size. The refuse moves through theconditioner chamber 23 at a rate which may be controlled in accordancewith the moisture content of the trash.

A hot air heater 25 forces hot air gas (subsequently mixed with steam)into chamber 23. Air is drawn through a compressor 87 and is forced bythe compressor into the hot air heater 25 and then forced into chamber23. A steam boiler 24 develops steam and forces the steam through asuperheater 28. Superheated steam leaves the superheater 28 and mixeswith hot air passing from heater 25 within chamber 23. Hot air enterschamber 23 via a ring structure 45, discussed below with reference toFIG. 3. The superheated steam may either be mixed with the hot air orinjected separately into chamber 23. If steam is injected separately, itmay be done so by a nozzle(s) and the steam may be deflected into thecenter of the chamber by rotating flute elements 72, describedhereinafter.

Boiler 24 can be fueled with unrecyclable waste paper for furtherefficiency, employing a conventional bag house 19 and a conventional ID(induced draft) fan 12 for pollution free operation.

Hot flue gasses from steam superheater 28 are split with some beingrecycled through duct 83 into chamber 23 with the balance exhausted tothe atmosphere at 20.

The temperature of the gas at the inlet to chamber 23 will range from250° F. to 550° F. The mixture of superheated steam and hot compressedair serves to kill bacteria inherent in the refuse in addition toshrinking and drying of the refuse. The steam will carry more BTU's ofheat than the air, as understood.

Midway through the conditioning chamber 23, the refuse is exposed to asecond stage reheater, generally indicated by reference numeral 29. Partof the air discharged from compressor 87 is heated to about 500° F. in aconvection bank 22, merged with line steam and discharged back throughline 89 to the second stage reheater 29 and into chamber 23.

Reheater 29 is formed from a distribution pipe 31 disposed along thelongitudinal axis of chamber 23. Located on the outer surface of pipe 31is a plurality of directional nozzles 33 through which the hot gas isdischarged.

Chamber 23 rotates about its longitudinal axis tumbling the refuse andcausing the refuse to move through the longitudinal length of thechamber. Distribution pipe 31 does not rotate with chamber 23.

Chamber 23 also contains a perforated inner liner 42. Liner 42 includesthree inch holes 44, each spaced approximately five inches from theircenters and covering the entire surface of liner 42. In addition, slots46.(about 6 inches by 18 inches) are cut in liner 42 along the face oflifters 70 (described hereinafter in reference to FIG. 7). As chamber 23rotates, materials 6 inches and smaller is scooped through the holes 44and slots 46.

The refuse passes through chamber 23 and exits at an outlet 35 into adropout box 37. The refuse cools rapidly and is conveyed by a mechanicalconveyor 39, as for example moving belts, which can be used to conveythe refuse to a mechanical classifier (not shown), or a hand pickingline (not shown), where glass, ferric, aluminum, large plastic items,textiles and paper are sorted and sent to respective areas for recyclingor disposal. The paper can further be separated into various.classifications for baling and shipment or used for fuel for generatingsteam.

The small sized refuse that passes through inner liner 42 falls intogrit box 20. Fine materials, such as food and other organics, grit,shrunken foam, shards of glass, etc., fall through a vibrating screen 48or similar sorting device, and are then disposed of in a landfill orcompost system. The larger items which fall into grit box 20 and do notpass through screen 48, such as soft drink cans, glass jars, shrunkenplastic bottles, etc., move onto a moving belt 50. Belt 50 may form apicking line or transfer the items to a mechanical sorter for recoveryand recycling of the items.

Referring now to FIG. 2, inlet passage 15 includes a slanted guideway 41which leads into a rectangular entrance 43 of the chamber, shown moreparticularly in FIG. 3. A primary hot gas nozzle ring 45 is disposed atthe entry end of chamber 23. As shown in FIGS. 3, 4 and 5, ring 45 isformed from a circular hollow pipe through which the hot air/steam gasis forced. A plurality of nozzles 47 communicate the interior of ring 45with the interior of chamber 23. Hot gas is forced into ring 45 via astem pipe 49 and then expelled through nozzles 47. The nozzles aredirected facing into the rotating chamber from the front thereof.

As shown in FIG. 2, chamber 23 is supported above the ground orhorizontal 50 by a plurality of support legs 55,57. As shown moreparticularly in FIGS. 11, 12, support legs 55, 57 support bearingsurfaces 51, 53 on which the chamber rotates. In addition, drop out box37 (FIG. 2) includes a circular bearing (not shown) which receives thechamber permitting its rotation relative to the drop out box. As shownin FIG. 12, legs 55, 57 include rollers 52, 54 which turn relative tothe legs during rotation of the chamber.

A motor assembly 65 is secured to the horizontal 50 and engages asprocket gear 64, positioned at the central portion of the rotatingdrum, for causing its continual rotation. As shown in FIG. 2, cylinder23 is formed of an outer skin 32 and an inner skin 34, between whichinsulation 36 is disposed. Perforated inner liner 42 (FIG. 2) ispositioned uniformly inside the conditioning chamber and extends intodropout box 37 and over the top of grit box 20. Refuse which does notfall through inner liner 42 exits the chamber into dropout box 37. Innerliner 42 rotates together with chamber 23.

As shown in FIG. 2, distribution pipe 31 is located along thelongitudinal axis of chamber 23. Pipe 31 lies within the majority of thecentral portion 61 of drum 23 and extends through dropbox 37. As shownin FIG. 6, distribution pipe 31 includes a coupling end 67 and a wearend 69. A wearplate 71 is formed around the outer perimeter of tube 31at the wear end 69.

As shown in FIG. 7, wear end 69 of tube 31 rotates within a support ring73 which is fixed with respect to chamber 23 by four support arms 75,77, 79, 81. As chamber 23 rotates, support arms 75-81 and support ring73 rotate relative to distribution pipe 31. As shown in FIGS. 8 and 9,directional nozzles 33 are positioned around the circumference of tube31 for providing forced hot gas within chamber 23. End 69 of tube 31 isclosed so that hot gas is forced only from nozzles 33.

Referring again to FIG. 7, a plurality of flute elements 83, formed offlat metal plates, are secured to the inner perforated liner of rotatingdrum 23 in an auger-type arrangement. Flute elements 83 serve totransport the refuse from entrance 43 of the chamber to its outlet 35.Flute elements 72 formed of flat metal plates (4 inches by 12 inches)are also located below the perforated liner 42 and attached to the innerskin 34, to convey the material out of the conditioner quickly. The flatplates 72 are positioned in an auger arrangement on the inner skin.Lifters 70 formed of flat metal plates (6 foot by 1 foot) are alsomounted longitudinally in a staggered arrangement around thecircumference of the perforated liner 42. Lifters 70 serve to lift andtumble the trash for better contact with the hot air/steam. Slots 46 arelocated at the base of the lifters 70 where the lifter meets the liner42.

Drop out box 37 is located at the outlet of chamber 23. Waste is movedinto the dropout box and falls by gravity into the bottom sectionthereof. Conveyor 39 is located at the bottom of dropout box 37 andserves to convey the removed refuse to the next processing section (notshown). The hot air gasses being forced through chamber 23 are led outof the top of drop out box 37 through steam superheater 28 (FIG. 1) tothe hot air stack 11 to the atmosphere at 20 or to chamber 23 via duct83.

Rotational controls 93, as shown in FIG. 1, are manually controllable bythe operator for controlling the motor assembly 65 for establishing therate at which chamber 23 rotates. The flutes within chamber 23 establishthe rate at which refuse is generally moved through the chamber from itsentrance to its exit ends. By changing the rate of rotation, theoperator can establish the amount of time that the refuse is withinrotating chamber 23 and, thus, the amount of time that heat is appliedto the refuse. Where the refuse has a good deal of moisture, theoperator can slow the rotating drum down to ensure that the refuse isproperly treated. The polyfoam plastic materials move through chamber 23in less than ten minutes. This may be slowed, as discussed, by theoperator, but the heating time will generally be less than ten minutes.

From the above description it can be seen that refuse includinghousehold bags of trash are fed into rotating chamber 23. No attempt ismade to shred the trash by mechanical or other means. Jets of hot airand superheated steam contact the refuse including bagged garbage andthe bags may open or be disintegrated by the steam contact. Polystyreneand other polyfoam materials are shrunk in size by controlled convectiveheat. Material six inches and smaller is filtered out. Glass andplastics are contacted with superheated steam making their subsequentremoval and sorting much easier and more sanitary.

While preferred embodiments of the invention have been describedhereinabove, those of ordinary skill in the art will recognize that theembodiments may be modified and altered without departing from thecentral spirit and scope of the invention.

What is claimed is:
 1. A trash conditioner for shrinking refuse,comprising:a rotatable chamber having an interior; means for rotatingsaid chamber; refuse inlet mean providing an entrance into said interiorof said chamber for movement of refuse therewithin; means for generatinghot gas at a temperature between 250° F. and 500° F. and for forcingsaid gas into said chamber; means for distributing said hot gas insidesaid chamber; and means for moving refuse:within said chamber during aminimum period of time during rotational movement of said chamber.
 2. Atrash conditioner according to claim 1 wherein said means for movingrefuse within said chamber during a minimum period of time comprises aplurality of elements located within said chamber, said elements beingarranged to form an auger conveyor.
 3. A trash conditioner according toclaim 1 and further comprising:means for separating the refuse intomultiple ranges of size refuse.
 4. A trash conditioner according toclaim 3 wherein said means for separating the refuse includes aperforated inner liner disposed in said chamber.
 5. A trash conditioneraccording to claim 4 wherein said perforated inner liner includes aplurality of apertures, the refuse moving through said chamber andhaving a dimension smaller than that of said apertures being separatedby passing through one of said apertures.